Source: Donít Shoot Your Food - SlashGear
"When people are extraordinarily happy with their food, they take a picture and share it. Why? Because they know their friends will relate. Because it makes them feel special and important to be eating something so tasty or unique. Because itís a way of marking where you are and telling people what you are doing. Whenever we travel abroad, we always make special note of the food. When you think about it, that seems odd.
We spend 3-4 hours a day eating, at most. So, 1/8 Ė 1/6 of the day is spent at meals. What about the rest of the day? Sure, you can have a great nightís sleep, but you donít take a picture of your bed afterword. When you have an easy commute, do you take a picture of the open road? When your boss is happy with a project youíve completed, you donít snap a picture and share it (confidentiality aside)."
To be honest I have more friends on FB who shares what they eat then those who goes for proper photography outings.